优良自交系是培育高产、稳产、抗病杂交种的物质基础。为了促进玉米生产的发展,1982年我们为石家庄地区种子公司繁殖玉米自交系黄早四10亩,获得单产205斤的好收成,我们采用的技术措施是:①安全隔离。为防止混杂退化,做到在自交系繁殖区四周千米内不种玉米。②粒选种子。将杂粒、异型粒、碎粒、霉烂粒拣出去。③适时早播,这 Excellent inbred lines is to cultivate high yield, stable yield, disease-resistant hybrid material basis. In order to promote the development of corn production, in 1982 we shredded maize inbreds Huangzao 4 10 mu for Shijiazhuang seed company and obtained a good yield of 205 pounds per mu. The technical measures we adopted are: ① safe isolation. In order to prevent hybrid degeneration, so in inbred breeding area within four kilometers of no kind of corn. ② seed selection seeds. The miscellaneous grains, shaped tablets, nibs, rotten grain picked out. ③ timely sow, this